[Measurement of the appearance of volatile fatty acids in the portal vein during digestion in conscious pigs].

A method used to measure the nutrient exchanges between the intestinal lumen and the portal blood was applied to 3 pigs receiving 800 g of a diet containing 6% of cellulose. During a postprandial period of 24 hrs., the mixture of volatile fatty acids (90 mM/h) appearing in the portal vein was composed of acetic acid (57%), propionic acid (30%), butyric acid (9%), isovaleric (2.5%) and valeric acid (1.5%). The composition of this mixture differed from that of the colic contents because of its acetic acid enrichment at the expense of butyric acid. The resulting energy supply to the animal represented about 600 to 700 kcal/24 hrs.